The invention relates generally to power plants, and more specifically to how the power output capacity of a power plant can be expanded.
In a more and more competitive market with more and quicker product changes, operators within the telecommunication field have a need of expanding the power output capacity of their existing power plants by adding power systems thereto without being restricted to just power systems from the manufacturer of the existing power plant.
In order for the manufacturer of the added power system to take on the responsibility for the combined power plant, the signal systems of the original power plant and the added power system should not be mixed.
It is known per se to extend the power output capacity of an existing power plant comprising a set of rectifiers by connecting an additional set of rectifiers in parallel with the existing set of rectifiers to a varying load.
So far, such an expansion has required the control systems of the two sets of rectifiers to be combined.
Most often, this is very difficult, since the control system of the existing power plant is totally unknown to the manufacturer of the added power system although the output voltage of the existing power plant is known.
The object of the invention is to bring about a method and an arrangement for expanding the power output capacity of a power plant without any need of having to combine any control systems.
This is attained in accordance with the invention mainly by shifting the operating range of the existing power system to higher current values by setting the added power system to supply, at the output voltage of said first rectifier, a constant load current that is lower than its maximum current.
Moreover, in response to maximum current from the existing power system, the added power system is controlled to supply load currents between the set constant load current and its maximum current. These load currents are supplied by the added power system at a predetermined lower voltage than the output voltage of the existing power system.
Hereby, the power output capacity of the power plant is expanded without any need of having to combine the two control systems.